In the field of a graphic art, a number of plate making films are used for photographing colors separately, composing images, and so forth, in the step of making a printing plate having thereon a halftone dot image formed out of a continuous tone image on a reversal film, color negative film, color paper, and the like. This makes processing so complicated that so many errors such as erroneous lettering, layouts and so forth cannot be avoided.
Furthermore, various corrections for lettering, layout, coloring and so forth are requested at random by clients, so that missing of the corrections is liable to take place. It is also necessary to make an advance check on whether a printed matter can be finished to meet the requirements of color tone and gradation.
For the purpose of making confirmation of this kind of proofreading, not only a proof-print system but also a variety of systems have been made public and available on the market. These systems include, for example, those using a CRT, those using non-silver light-sensitive materials comprising a photopolymer, diazo compound or the like, those forming an image with a dry toner, an electro-photographic system, and so forth. However, these proofreading systems have the problems such as a long time required to finish a proof sheet, an expensive material cost, a poor workability, and so forth, so that they can not be the systems satisfactory for practical use.
The other systems than the above for preparing a proof include a system in which a color-separated halftone original is printed on a color light-sensitive material through color-separated light. These systems include a method in which a proof is obtained on a color light-sensitive material through a photographing system by making use of a projection lens, disclosed in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 60-4276/1985, 62-280746/1987, 62-280747/1987, 62-280748/1987, 62-280749/1987, 62-280750/1987 and 62-280849/1987, and so forth; or a contact exposure system under marketing by Chesley F. Carlson with a trade name of `The Carlson Proofmaster System` and by Kreonite Inc. with a trade name of `Color Proofing System`, respectively.
Either system using a positive or negative type silver halide color photographic light-sensitive material enables to perform color proofreading at less cost in shorter time and comprises more excellent characteristics than the other systems.
In these systems, the color-separated B/W halftone dot images which are formed by subjecting a color original to color separation for converting to the halftone dot image are printed one after another on a sheet of color paper in a contact printing method, and the printed color paper is subjected to color developing to form the color images with the dyes produced imagewise from the couplers. The resulting color images are used for proofreading.
In addition to the foregoing systems, a silver dye bleaching system is known. However, this system is unsuitable for a proofreading image forming system where an ever stable and high quality image is required, because of a defect that processings are unstable.
In this regard, a proofreading image forming system where a color image is formed by coupling of a coupler and an aromatic primary amine type developer on a silver halide color photographic light-sensitive material has an advantage that a stable quality image can be prepared.
In such a process, it is required for a color paper that a hue of a dye image produced from a coupler is close to that of a printed color image. At present, however, no such technical requirements have ever been fully satisfied.
With respect to this technical problem, such method is disclosed in Japanese Patent Application O.P.I. 62-109055/1987 that a hue of a magenta image can be closer to that of a printed matter by exposing a magenta color-separated negative to blue light and additionally to green light. As described in the foregoing application, however, no any satisfactory approximation of a hue can be achieved by controlling an exposure on an ordinary color paper.
Japanese Patent Application O.P.I. 61-47957/1986 and 61-28948/1986 disclose that combined use of a pyrazoloazole type magenta coupler and alkyl phosphate can reduce a subsidiary absorption in a longer wavelength region, while it does not disclose an application for a color proof. Therefore, a hue of a color proof image of which density is expressed by that of a halftone dot can not be anticipated only from a hue of an ordinary photographic image and a spectral absorption.
Further, an approximation of a hue in some limited area (limited halftone area) does not necessarily result in completely satisfying the conditions required to a color proof, and therefore, a high approximation of a color image in all area from a highlight to a shadow is necessary for preparing a color proof having a hue of a further higher approximation.